Speckle interferometry at 10 micrometers wavelength: a combined thermography and interferometry technique and its application in aeronautical nondestructive testing

Abstract

Speckle interferometry with CO 2 laser (10 micrometers) and microbolometer array has been developed and the final outcome is a mobile interferometer. The long wavelength allows to measure large deformations and is well immune against external perturbations, so as it can be used in field conditions. The technique is based on specklegram recording on the microbolometer array. The background of the specklegram is constituted by the thermal image of the object. Consequently the technique allows simultaneous observation of deformation and temperature difference when an object undergoes a given stress. We show several applications in aerospace nondestructive testing.